Well...
Home Emergency Cover was a bit of a bust.
Sure, they came out but as soon as they were told that an engineer had come out on Monday (i.e. the previous day), they wouldn't touch it - even though the heating was faulty.
Usual story - anything an insurance company can do to avoid paying out a claim (or in this case, doing something under the terms of the policy) they find a way to wriggle out of their obligation. They are less ethical than bank robbers imho.
Anyhow, our engineer returned Friday to sort out the issue (he'd had a domestic issue on the Monday which meant that he was keen to return home and didn't do his customary checks to make sure the issue was fixed before leaving. He 'fixed' what he thought was the problem then left thinking it was sorted (it wasn't).
So, on Friday he finds two issues with the CH system.
1) The room stat on the main heating zone (basement floor and ground floor) was apparently closed all of the time
and
2) One of the zone valves was very stiff - meaning that the powerhead could open the valve but the return spring wasn't strong enough to close the valve again when required - meaning the valve was permanently in the open position and allowing water to flow around the DHW cylinder - with the result that the DHW was constantly too hot - heading towards 60C coming out of the tap despite the DHW being turned off at the boiler.
Could the permanently open valve have caused the room stat to weld closed? I can't actually get inside the thermostat to see what the contacts are actually doing (I can get inside the thermostat but the contacts appear to be inside a small black box - looking rather like a relay).
So new mechanical valve and a new room stat and the heating now seems to be doing what it should.
However, the new room stat doesn't seem to be at all accurate - it seems to be around 3-4C "too high" (in other words it is saying that the temperature is 20C when two liquid thermometers are saying 16C and 17C).
Is there any way to adjust these? The thermostat in question is this one from
Screwfix >>
DRAYTON RTS1 ROOM THERMOSTAT
It looks like there isn't a way to alter the stat so that the point at which it switches matches the room temperature!
Is this a 'known issue' with these thermostats?
The old thermostat was an ACL RTS 1 (see below)
I may have a look at the RTS2 >>
Drayton RTS2 and see if that is any better.
Also possibly looking at a digital thermostat such as the
Honeywell Home (DT90?)
The old ACL and new RTS1 have only 3 wires - neutral and live feed and a switched live to boiler.
Looking at the DT90 wiring diagrams - it doesn't seem to be as simple as just swapping them over - none of the 6 diagrams (a - f) seem to match the wiring I have for the current stat.
If I chose the DT90 Digital Thermostat - how simple would it be for me to swap the stats over?
Any help gratefully received (and comments about the 3-4C difference between the room temperature and the RTS-1 setting. Have I simply got a bad example?)
Wiring for room stat (and rear of new RTS-1) are below:
Cheers,
XRD
